What is Pulmonary Transplant?

A Pulmonary Transplant includes different procedure options: single-lung transplantation, double-lung transplantation performed by using a bilateral sequential single-lung procedure, heart-lung transplantation and lobar transplantation donors. Double-lung transplantation is necessary in patients who have septic lung disease such as diffuse bronchiectasis or cystic fibrosis because of the risk of infection in the transplanted lung if the residual lung were left in place. Heart-lung transplantation is a clear indication in patients who have Eisenmengers syndrome without correctable cardiac defects, pulmonary disease with unrelated heart disease and chronic thromboembolic pulmonary arterial hypertension when thrombendarterectomy is not feasible. Single-lung transplantation is the most commonly used procedure in patients who have emphysema. Lung transplantation has resulted in improved quality and length of life in many patients. However, they are frequently accompanied by profound side effects.

Noncardiogenic pulmonary oedema commonly occurs in the transplanted lung shortly after its reimplantation (reperfusion, oedema). The radiological findings of such a reperfusion injury are nonspecific and similar to those in patients who have left ventricular failure, fluid overload and acute rejection. They range from a subtle perihilar haze to patchy or confluent air-space consolidation involving mainly the middle and lower zones. Peribronchial and perivascular thickening and a reticular pattern are also present in most patients. The oedema usually begins immediately after transplantation, worsens over the first 2 days and peaks in severity between the second and fourth postoperative day, or later in case of heart-lung transplantation.

Acute rejection is an almost invariable complication of lung transplantation and an important cause of morbidity. It occurs mainly within the first two months after transplantation. Clinical symptoms and signs include cough, dyspnoea, fever, tachypnoea and crakles on auscultation. The radiographic findings include a fine reticular pattern, interlobular septal thickening, ground-glass opacities, patchy or confluent air-space consolidation and new or increasing pleural effusion. The diagnosis often depends on transbronchial biopsy. A favourable response may be obtained from high doses of intravenous corticosteroids.

Bronchiolitis obliterans organizing pneumonia (BOOP) may be associated with mild acute rejection or seen in the context of infection, usually cytomegalovirus CMV pneumonia. Rarely, it occurs as an isolated finding. It may follow or precede the development of constrictive bronchiolitis. Radiological features of transplantation-associated BOOP are similar to those of idiopathic BOOP in the nontransplant population.

Constrictive bronchiolitis is generally recognized between 6 and 12 months after transplantation. The clinical course is variable, the disease may have an insidious onset and indolent progress or a rapid evolution. In clinical practice, the diagnosis of constrictive bronchiolitis is usually based on a combination of clinical, radiological and functional findings. Bronchoscopy and transbronchial biopsy are useful diagnostic procedures. The radiographic findings include decreased peripheral vascular markings, decreased or increased lung volumes and bronchial dilatation. HRCT scans show bronchial dilatation, bronchial wall thickening and mosaic perfusion with air trapping (Fig. 1). The dilatation involves mainly the segmental and subsegmental bronchi of the lower lobes.

Post-transplant lymphoproliferative disorders (PTLD) may occur from about 5% to 20% of lung transplant recipients. Most cases present in the first year after transplantation. The most common radiological findings consist of single or multiple nodules, patchy areas of air-space consolidation and hilar or mediastinal lymphadenopathy. Most patients who have polymorphic, benign appearing lesions  histologically, have clinically unsuspected disease, solitary pulmonary nodule at presentation and better survival (Fig.2). Patients with monomorphic proliferation most commonly present in the allograft as multiple nodules or multiple areas of air-space consolidation and a lower survival.

After lung transplantation the necessity of preventing graft rejection by chemotherapeutic immunosuppression is associated with a significant risk of infection, often severe and caused by opportunistic organisms. Pulmonary infection is the most common cause of morbidity and mortality in lung transplant recipients. The spectrum of organisms include a variety of bacteria, viruses (CMV), fungi (aspergillosis, candida and pneumocystis carinii) and mycoplasma species.

Mechanical complications may occur on the bronchi and pulmonary vessels after lung transplantation. The two main bronchial complications related to the anastomosis are bronchial dehiscence and bronchial stenosis. The former usually occurs in the first few months after transplantation, sometimes related to the infection at the anastomotic side. Both bronchial dehiscence and stenosis can be easily recognized on CT. Most stenoses can be managed successfully with stent insertion (Fig.3). Complications related to the vascular anastomosis are uncommon. Pulmonary arterial or venous obstruction, as well as lobar torsion have been reported.

Imaging Examples

Transplant, pulmonary, Fig.1
Transplant, pulmonary, Fig.2
Transplant, pulmonary, Fig.3 (a)
Transplant, pulmonary, Fig.3 (b)

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Last Updated: Feb 10, 2010

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